pub fn odd_fibnacci_sum(threshold: u32) -> u32 {
  let mut a = 0;
  let mut b = 1;
  let mut sum = 0;

  while b < threshold {
    if b % 2 != 0 {
      sum += b;
    }
    let next = a + b;
    a = b;
    b = next;
  }

  sum
}
